He was fearless, everyone in the village lived in mortal fear of him. In battle, he would fight with his claws and teeth and poisoned his opponent and so he was always victorious. Drogon was both good and bad, he would protect his people from external harm but if any of his people stand against them, with a swipe of his hand, he would slit their throats.
He wasn't always like this, he was a good man but when the beasts attacked his village, he allowed himself to be used as the protector against the beasts and in doing so, he changes into a monster.